1. Field of the Invention
The present invention relates to a trim hold down box apparatus for assisting in the separation of trim cut from an edge of a sheet. More particularly, the present invention relates to a trim hold down box apparatus for assisting in the separation of trim cut from an edge of a sheet by a cutter prior to the sheet being transferred from a forming wire of a forming section to a press section of a paper making machine.
2. Background Information
In the papermaking art a typical papermaking machine will include a forming section where paper stock is ejected as a ribbon onto a moving wire screen where water drains from the paper stock to form a formed web.
The formed web is then transferred from the forming wire or screen into a press section for pressing more water from the web. The press section usually includes a pick up roll which is disposed closely adjacent to a turning roll of the forming section, the pick up roll being provided with vacuum segments for initially transferring a tail cut from the formed web. The tail is then widened until a full width sheet is being transferred from the forming wire to the pick up roll of the press section. However, before transferring the formed web into the press section, it is usual for the formed web to be transported by the forming wire around the turning roll of the forming section where the formed web is released from the forming wire to a couch pit for recycling thereof. Such releasing of the web to the couch pit is continued until the formation of the web on the forming wire has been adequately stabilized. When the web has been stabilized, a cutter disposed upstream from the pick up roll cuts the web in a machine direction so that a narrow trim is removed from the edge of the formed web, with the trim and the remainder of the full width sheet being released to the couch pit. The aforementioned tail is then cut in a machine direction so that on application of vacuum to the pick up roll, the tail will transfer from the forming wire into the press section while the trim continues on the wire to the turning roll for release to the couch pit. However, a problem has existed in prior art forming sections in that although the trim is cut from the web, there exists a tendency for the trim to fail to fully separate from the sheet and for the trim sometimes to be transferred with the sheet into the press section. When such trim extends through the press section, the quality of the resultant paper is compromised and the web often tends to break in the press section thus resulting in lost production.
The present invention overcomes the aforementioned problems by the provision of a trim hold down box apparatus that positively separates the trim from the sheet so that the trim is prevented from being transferred by the pick up roll into the press section.
Therefore, it is a primary feature of the present invention to provide a trim hold down box apparatus that overcomes the problems associated with the prior art arrangements.
Another feature of the present invention is the provision of a trim hold down box apparatus that enables reliable separation of trim from an edge of a sheet when transferring the sheet from a forming section to a press section.
Other features and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description of a preferred embodiment of the present invention contained herein.